Aerate to Control Grain Temperature

Cool grain to less than 60°F as soon as possible after harvest by running aeration fans during cool weather. In the late summer, this might mean running fans only at night. Don’t worry too much about high nighttime relative humidity during aeration because grain rewets much slower than it cools.

In late fall or early winter, use aeration fans to cool the grain to 20 to 30°F for winter storage. If the grain is not stored at less than 20°F during winter, you shouldn’t need to run fans to warm the grain in spring. If you do run fans in the spring, start early in the season (March or April) and make sure you don’t warm the grain beyond 40°F. Cooling grain limits mold and insect activity and it reduces moisture migration. Moisture migration can result in rewetting and eventual spoilage of the grain at the top center of inadequately cooled bins.

Estimate the number of hours a fan must be operated to cool a bin of grain by dividing the number 15 by the airflow in cfm/bu. For example, it takes about 15/0.2 = 175 hours, or about three days of fan operation to cool the grain.